The present invention relates to a magnetic valve for controlling a flow opening of a connecting line for guiding fluid, in particular fuel.
More particularly it relates to a magnetic valve which has a valve housing with a guide bore hole, and a valve member actuated by an armature of an electromagnet and displaceable in the bore hole so as to be brought in contact with a housing valve seat.
Magnetic valves of the above mentioned general type are known in the art.
In such a magnetic valve which is known from FR-A 2 171 342, the armature is constructed as a coupling member and has an axial pocket bore hole with a flanged edge at its outlet and holds a spring disk by this flanged edge as coupling member. The spring disk is acted upon by the coupling spring which is tensioned in the pocket bore hole. The valve member is acted upon axially in the direction of the coupling member by a return spring and is thus held in contact with the spring disk in such a way that the valve member follows the armature against a return spring when the armature or .coupling member is attracted. When the electromagnet is not excited, the armature is returned by the return spring and the valve member is pressed on a conical seat with its sealing surface. In a continued movement of the armature the spring disk of the coupling member can be lifted by the valve member from the flanged edge of the pocket bore hole in the coupling member against the force of the coupling spring. The coupling spring provided in this magnetic valve has a greater rigidity than the return spring and serves to compensate for a possible divergence in path between the armature and valve member and accordingly makes it possible to allow higher tolerances in the manufacture of the magnetic valve or different temperature expansions of the individual parts while still providing a high closing force.
A problem in fast-acting magnetic valves is that of the bouncing of the valve member after the valve closes. When such a magnetic valve is used in fuel injection pumps, a reopening of the valve member due to bouncing leads to unacceptably large fluctuations in the amount of injected fuel. Although the bouncing of the valve can also be ameliorated by the resilient coupling between the armature and the valve member known from the prior art in that a constant closing force takes effect at the moment that the valve member contacts its valve seat, such a valve is still in need of improvement. In particular, oscillating movements of the coupling spring can also occur in this valve.